Post-Op Acute Kidney Injury Not Prevented by Aspirin, Clonidine

Aspirin and clonidine increased the risk of major bleeding and clinically important hypotension.

PHILADELPHIA—Neither aspirin nor clonidine administered before and after non-cardiac surgery decreases the risk of acute kidney injury (AKI), according to study findings presented at the 2014 Kidney Week meeting and published simultaneously online in the Journal of the American Medical Association.

Previous research has suggested that aspirin or clonidine given during the perioperative period decreases AKI risk. The new study, led by Amit X. Garg, MD, PhD, of the London Health Sciences Centre and Western University in London, Ontario, included 6,905 patients undergoing non-cardiac surgery and compared aspirin or clonidine with placebo.

In the aspirin versus placebo part of the study, the investigators randomly assigned patients to take 200 mg aspirin or placebo 2 to 4 hours before surgery and then take 100 mg aspirin (100 mg) or placebo daily for up to 30 days after surgery.

In the clonidine versus placebo part of the study, they randomly assigned patients to take 0.2 mg of oral clonidine or placebo 2 to 4 hours before surgery. A transdermal clonidine patch or matching placebo was then applied to the skin, where it remained until 72 hours after surgery.

AKI developed in 13.4% and 13.0% of the aspirin and clonidine recipients, respectively, and 12.3% and 12.7% of placebo recipients, Dr. Garg reported during a press conference. These differences were not statistically significant.

In addition, Dr. Garg noted that aspirin increased the risk of major bleeding, and this was associated with an increased risk of AKI (23.3% when bleeding was present vs. 12.3% when bleeding was absent). Clonidine increased the risk of clinically important hypotension, which was associated with an increased risk of AKI (14.3% when hypotension was present vs. 11.8% when hypotension was absent).

The researchers defined AKI as a 0.3 mg/dL or greater increase in serum creatinine within 48 hours of surgery compared with before surgery or an increase of 50% or greater within 7 days of surgery.